1. Field of the Invention
The present invention relates to a fuel supply control system for an engine, which is adapted to control opening and closing of an air vent system which provides communication between an upper space in a fuel tank and the atmosphere, and opening and closing of a fuel passage system which provides communication between a portion of the fuel tank below a fuel oil surface and a fuel supply section in the engine.
2. Description of the Related Art
Japanese Utility Model Application Laid-open No. 62-93145 discloses a conventional fuel supply control system for an engine, wherein a negative-pressure responsive type automatic fuel cock adapted to be opened by a negative pressure generated in a negative pressure generating section in the engine is incorporated in a fuel passage which provides communication between a portion of the fuel tank below a fuel oil surface and a fuel supply section in the engine, so that upon stoppage of the operation of the engine, the fuel passage is automatically blocked by the automatic fuel cock to inhibit flowing-down of a fuel from the fuel tank to the fuel supply section in the engine.
With such a conventional fuel supply control system for the engine, the flowing-down of the fuel from the fuel tank to the fuel supply section in the engine can be inhibited by the automatic fuel cock upon stoppage of the operation of the engine, but an upper space in the fuel tank is put in a state in which it is opened to the atmosphere through an air vent, so that if an evaporated fuel is produced in the fuel tank, the evaporated fuel is released into the atmosphere through the air vent.